All of a sudden, it's has a hard starting issue.

[bossbob]

I put the pressure tester on it this morning, cold engine was 0 psi. Rocked the key on and off, I could hear the fuel pump cycling and built the psi up to 20. Started the engine and max psi was 25. No fuel coming out of the return line with just the key on.

I reinstalled the old FPR and even though it doesn't hold pressure, it runs at 38 psi at idle.

If I disconnect the vacuum line and plug it the engine runs better and smoother at idle, but didn't test it under load.

Does it still sound like I need to pull the tank.

Either one still runs crappy like it's starving for fuel. At idle the engine is surging, under load it is hesitating.

 

[RonD]

Those are odd results
I have seen FPRs not hold pressure, so leak fuel out Return line port, when pressure is under, say 15psi, but once above 15psi they seal tight from the higher pressure, yes odd.

And new one is faulty, if it is releasing pressure under 30psi, especially with vacuum hose disconnected, since old one gets up to 35+ psi, system/pump can maintain that pressure, so new FPR is bad.
Return it

Put vacuum hose on old FPR and suck on it, see if it holds vacuum, could be its diaphragm is leaking vacuum causing vacuum leak in engine at idle, rough idle.

Not sure what to tell you at this point

 

[bossbob]

Ron,

As I mentioned the gas gauge didn't work, I put 5 gal. of gas in, and it ran great. Funny thing is I only got about a 150 miles out of a full tank?

Anyway, a guy stopped by and bought the truck, so, no longer a problem.

Good news, is I'm going to look at a 89 4x4 this afternoon. So, will most likely post more questions on a different ride.

Thanks for all your help.